Abstract: A circuit for sensing the presence of an inductive load that is particularly applicable to sensing when a solenoid is being driven by a pulse width modulation (PWM) signal. The circuit includes a high side connected transistor having an output driving a load, with the transistor driven by a PWM signal. A circulating diode is coupled to the driving output of the transistor. The circuit further comprises an operational amplifier (op amp) circuit that is coupled to the circulating diode and operates as an inverting operational amplifier (op amp). The op amp circuit charges a first capacitor when the transistor releases driving an inductive load.

Abstract: The present invention provides a Driver circuit having dynamically adjusting output current and limiting input current function. This present invention dynamically adjusts the output current provided by the driver unit to reduce this output current in real time. A protection circuit is also provided to limit the input current supplied to the driver unit. This present invention avoids overdriving the driver unit.

Abstract: A circuit and method are given, to realize a high-voltage control and driver interface as integrated circuit, especially for use in connection with four external components, inductor L and capacitor C as well as low-side and high-side switching transistors as found e.g. in half-bridges. The circuit is essentially self supplied by means of an Intrinsically floating auxiliary supply power generation and regulation scheme. The circuit is apt to supporting high main supply voltages up to 1000V. The circuit of the invention is realized without the need for any internal high-voltage integrated semiconductor devices. Exploiting the advantages of that solution the circuit of the invention is manufactured with standard CMOS technology and only four discrete external components, which is favorably lowering the cost of production.

Abstract: A circuit configuration for driving a semiconductor switching element includes an output terminal for the connection of a semiconductor switching element, a capacitive charge storage configuration, which is coupled to the output terminal, a charging and discharging circuit having at least one input for feeding in at least one drive signal and an output connected to the capacitive charge storage configuration, and a discharging circuit with a connecting terminal. The connecting terminal is connected to the capacitive charge storage configuration and provides a discharging current for the charge storage configuration. A charging current or a discharging current for the capacitive charge storage configuration is available at the output depending on the drive signal. A method for driving the semiconductor switching element is also provided.

Abstract: An excitation control circuit for suitably exciting a solenoid while current consumption and heating are effectively reduced. The control circuit has a driving circuit for driving a coil of a solenoid in response to a pulse signal supplied from an external device; a counter-electromotive force absorbing circuit, inserted in a path of a return current of the coil, for absorbing counter-electromotive force produced by the coil; and a return current circuit, connected in parallel to the counter-electromotive force absorbing circuit, for intermittently bypassing the return current. The return current circuit may have a field effect transistor switched on according to a signal for defining the timing of bypassing the return current, where the current path of the transistor is connected between a positive electrode and a negative electrode of the coil.

Abstract: The present invention relates to a circuitry for impedance matching. The invention utilizes circuitry for impedance matching, which circuitry for example is connected to a differential or balanced power amplifier or some other device in need of output impedance tuning. The circuitry includes at least one inductance connected to at least one device which conducts when being forward biased, and a direct current (DC) source controlling the conduction of the device. The circuitry eliminates the DC component of a signal passing through it. By controlling the device that is conducting when it is forward biased, it is possible to turn the circuitry on and off, thus altering the impedance at the output of the amplifier. Hence, a load switch has been created at the output of the amplifier.

Abstract: The present invention provides techniques for generating an intense magnetic pulse very quickly. The present invention includes a device that drives high current through a write head, which generates a burst of magnetic flux that in turn generates a high-intensity fringing field. To rapidly build up the current through the write head, the write head is coupled to a high voltage source. A switching circuit prevents current from flowing in the write head. In response to a signal from a control circuit, the switching circuit provides a path for current to flow through the write head. Current flow through the write head rises rapidly, which causes a burst of magnetic flux and generates a high-intensity magnetic fringing field. The high-intensity fringing field may be used to write to a magnetic medium.

Abstract: An apparatus for monitoring a device (such as a solenoid) powered by the apparatus includes a power supply for providing an alternating power signal to the device and a monitoring circuit that measures a prescribed characteristic of the alternating power signal. A control circuit is responsive to measurements from the monitoring circuit and is arranged to analyze the measurements to determine the status of the device therefrom.

Abstract: In a magnetic recording writing circuit, a current having a higher level than a write current is supplied for a period of time during rise and fall of the write current, and a current having a lower level than the write current is supplied for a period of time during overshoot at the rise and fall of the write current. Accordingly, the write current can recover quickly from overshoot.

Abstract: A line driver provides an output signal onto an output. The line driver includes a first current driver coupled to a first terminal of the output. The first current driver is capable of providing a first current to the first terminal that is sufficient to cause an output voltage having a magnitude Y to appear across the output. The first current driver includes a first plurality of elements to provide the first current to the first terminal of the output, each of the plurality of elements having a maximum voltage tolerance that is less than the magnitude Y.

Abstract: A technique for presenting an optimally timed control signal to an upper H-switch driver in a fashion capable of achieving a very fast transition of the current in the inductive recording head. The technique also provides a current boost during the transition while resulting in minimized power consumption at other times.

Abstract: A sensing apparatus having a fluxgate and a control method capable of reducing current applied to drive the fluxgate are disclosed, the sensing apparatus including a driving coil for exciting a magnetic substance core with current, a current amplifier for applying the current to first and second ends of the driving coil, a fluxgate having a pulse generator for generating a pulse to turn on/off the current amplifier, an A/D converter for converting an analog signal from the fluxgate into a digital signal, and a pulse controller for outputting a control signal allowing the pulse to be applied to the current amplifier until it is determined that the conversion of the analog signal into the digital signal by the A/D converter is completed.

Abstract: A write output driver with internal programmable pull-up resistive devices is disclosed. The write output driver provides an integrated output driver circuit configurable to provide near end transmission line termination. The output driver is configured to provide transmission of a high-speed signal with increased frequencies over prior output drivers. The output impedance of the output driver is programmable and maintained substantially constant, despite ambient fluctuations. An internal bias signal generator is provided to control the impedance of the output driver.

Abstract: An inductive load driving circuit includes a switching transistor and a guardring. The switching transistor is connected between an output terminal and a power supply potential point. The guardring is an N-type semiconductor region provided for the switching transistor and connected to the power supply potential point.

Abstract: An H-type bridge circuit includes four transistors, two resistors, and a write head. A write current supplied from a current supply circuit including a first of the transistors and resistors flows through the write head and is received in a current receiving circuit including a second of the resistors and a fourth of the transistors, and another write current supplied from a current supply circuit including the second of the transistors and the second resistor flows through the write head and is received in a current receiving circuit including the first of the resistors and the third of the transistors. Impedance of the write head matches an output impedance of the current supply circuit and matches an input impedance of the current receiving circuit.

Abstract: A low side switching driver circuit (50) includes an emitter follower circuit, an input buffer (51), and a power source (52) and capacitors (53, 54) for driving these circuits. The power source (52) is not provided for each one of low side switching elements (5, 6, 7), but the low side switching elements (5, 6, 7) use the power source (52) as a common power source thereamong. A resistor (58) is provided between the node between the negative pole of the capacitor (53) and a first low potential power source line, and a second low potential power source line (G) of the low side switching driver circuit. The capacitor (54) is connected to the input buffer (51). Resistors (59, 60) as current limiting elements are provided between the input buffer (51) and the power source (52).

Abstract: A write head circuit is provided having improved transient and steady state response. The circuit includes a dynamically coupled damping circuit that is coupled to the write head during transient periods of a write signal to substantially reduce or eliminate overshoot generated by a write head cable. During steady state or data writing periods, the damping circuit is decoupled from the write head to prevent unnecessary loading of the write head. In preferred embodiments, the damping circuit includes a resistor in series with a capacitor, and the damping circuit is coupled in parallel to the write head. The resistor substantially reduces the overshoot of a write signal supplied to the write head, while the capacitor decouples the resistor from the write head during steady state or data write periods.

Abstract: A circuit for driving an inductive load includes a high frequency driver and low frequency driver. A low frequency component and a high frequency component is taken from an input signal. The separate low and high signal components are driven by a low frequency driver and high frequency driver, respectively. The outputs of the low frequency and high frequency drivers are combined by combination circuitry. The high frequency component is amplified by the combination circuitry in addition to being combined. The output of the combination circuitry drives an inductive load at fast speeds. The driver circuit of the present invention may be configured to provide low noise at low frequencies, pass band limitations at the load terminal, different AC and DC open loop gains, and other characteristics depending upon system requirements.

Abstract: A method (and magnetic recording circuit structure) for write drivers to reduce the reversal time for the current through the inductive recording head, includes a write driver output stage providing a write signal output with a write signal source strength SO, a magnetic write head with a write signal input essentially equal to strength SO, and an interconnect circuit having a characteristic impedance ZO coupled to the write signal output of the write driver output stage and the magnetic write head. The write driver output stage preferably includes a source-side termination circuit having output impedance ZS, wherein the source-side termination circuit output impedance ZS is substantially equal to ZO and the source strength SO of the write driver at the input of the interconnect circuit is temporarily enlarged after every polarity reversal of the write signal for a predetermined time duration &Dgr;t.

Abstract: A disk drive system including a write circuit for controlling current through a magnetic write head includes an H-switch circuit and a pulse-mode power supply circuit. The H-switch circuit controls direction of current through the magnetic write head. The pulse-mode power supply circuit is connected to the H-switch circuit for providing a higher voltage pulse at a beginning of a switching event of the H-switch circuit to accelerate a change in direction of current through the write head, followed by a lower voltage until a next switching event.

Abstract: A disk drive system including a write circuit for controlling current through a magnetic write head includes an H-switch circuit and a charge-pumping circuit. The H-switch circuit controls direction of current through the magnetic write head. The charge-pumping circuit is connected to the H-switch circuit for storing energy during a first state of the H-switch circuit, and delivering energy upon switching from the first state to a second state of the H-switch circuit to accelerate a change in direction of current through the write head.

Abstract: A technique for presenting an optimally timed control signal to an upper H-switch driver in a fashion capable of achieving a very fast transition of the current in the inductive recording head. The technique also provides a current boost during the transition while resulting in minimized power consumption at other times.

Abstract: An Automatic Noise Reduction system wherein the Q of the frequency response is reduced using a negative output resistance to substantially eliminate the coil resistance of a speaker in a headset. The resulting system is less sensitive to variations in operating parameters, such as headset fit on a user and component variations. Temperature compensation of a negative output resistance amplifier is introduced to maintain stability over a wide range of operating temperatures. Temperature compensation includes substantially matching the temperature coefficient of the negative output resistance amplifier to the temperature coefficient of the speaker coil.

Abstract: To improve a control circuit for at least one inductive load, comprising a first load branch, which lies between a first voltage terminal and a second voltage terminal and comprises an electronic switch and the inductive load connected in series, the electronic switch lying between a first terminal of the inductive load and the first voltage terminal, and a second terminal of the inductive load being in connection with the second voltage terminal, a freewheeling diode, via which a freewheeling current of the inductive load flows when the electronic switch is open, in such a way that smallest possible fluctuations of the supply current and smallest possible voltage peaks occur at the voltage terminals, it is proposed that there is provided a freewheeling branch which has, as a series connection, a capacitance connected to the first voltage terminal and an inductance connected to the second terminal of the inductive load, and also a freewheeling diode lying between a center tap between the capacitance and the i

Abstract: A current feed circuit for feeding a high-frequency current to a plurality of sensor coils in a coordinate input device includes a high-frequency signal transmitting circuit for generating a high-frequency current corresponding to a high-frequency signal input; a plurality of driver transistors, each being provided between the high-frequency signal transmitting circuit and each of a plurality of sensor coils for transmitting the high-frequency current to the corresponding sensor coil; and a plurality of switches, each being provided with respect to each of the plurality of driver transistors for turning on/off the corresponding driver transistor.

Abstract: A system and apparatus for controlling a motor or other multi-directional load using an H-bridge circuit having self-latching, high side switches. Thyristors are used as high side switches, and arranged to self-latch. The H-bridge thyristors are also arranged to automatically discontinue the triggering gate current upon the thyristor switch closing to conduct current, which advantageously terminates the flow of gate current as soon as it is no longer required.

Abstract: An ultra-fast drive circuit (40) providing a rail-to-rail drive voltage at an output node (N1). A pair of bipolar output transistors (Q3, Q4) are selectively driven via a FET drive circuit (42), and by a control circuit (44) to achieve a rail-to-rail output voltage (Vcc−Vee) that is very fast. The drive FETs comprise three serially connected FETs (M5, M6, M7) whereby the middle FET (M6) is the control FET effecting the control of the output transistors (Q3, Q4). The other two FETs (M5, M7) are always in the on state and complete either the pull-up or pull-down of the voltage at the output node (N1), depending on the state of the middle FET (M6). The control FETs (44) provide two output control signals (46, 48) to the output transistors (Q3, Q4), with the control line (48) controlling the state of the middle switching FET (M6).

Abstract: An H-type bridge circuit having transistors Tr1 to Tr4, resistors R1 and R2 and a write head is disposed. A write current supplied from a current supply circuit having the transistor Tr1 and the resistor R1 flows through the write head and is received in a current receiving circuit having the resistor R2 and the transistor Tr4, and another write current supplied from a current supply circuit having the transistor Tr2 and the resistor R2 flows through the write head and is received in a current receiving circuit having the resistor R1 and the transistor Tr3. An impedance of the write head matches with an output impedance of the current supply circuit and matches with an input impedance of the current receiving circuit.

Abstract: A varnish composition, an inductive core made with the varnish composition, and methods of making the varnish composition and the core. The varnish composition includes an acrylic copolymer compound, a cosolvent having at least one of amine and amide functionality, and water. The varnish composition yields high bond strength when there are extended air dry periods prior to curing.

Abstract: A power semiconductor device includes an input signal processor circuit to which control signals are input, and power device driving circuits for individually driving power devices based on output signal of the input signal processor circuit. Level shift circuits are individually inserted between the input signal processor circuit and the power device driving circuit on a p-side and between the input signal processor circuit and the power device driving circuit on an n-side to electrically insulate GND lines for the p-side and n-side power device driving circuits and a GND line for the input signal processor circuit.

Abstract: A power semiconductor device includes an input signal processor circuit to which control signals are input, and power device driving circuits for individually driving power devices based on output signal of the input signal processor circuit. Level shift circuits are individually inserted between the input signal processor circuit and the power device driving circuit on a p-side and between the input signal processor circuit and the power device driving circuit on an n-side to electrically insulate GND lines for the p-side and n-side power device driving circuits and a GND line for the input signal processor circuit.

Abstract: An improved method and apparatus for active line termination is disclosed. An active termination line driver (ATLD) includes a pair of power amplifiers configured to amplify a transmit signal, the amplifiers comprise a first input for receiving the transmit signal, a second input for receiving a feedback signal, and an output configured to provide the amplified transmit signal to the load. The ATLD also includes a resistive network configured to provide the feedback signal from the outputs of the amplifiers to the second inputs power amplifiers. The resistive network is selectively configured to facilitate any one of a plurality of feedback configurations to emulate a back-matching impedance. Other embodiments of the present invention may be construed as methods for power efficiently driving a transmit signal to a load.

Abstract: There are included a switching circuit for flowing pulse electrical current through a primary winding of a transformer, a half wave rectification circuit or a full wave rectification circuit for extracting electrical current from a secondary winding of the transformer while this pulse electrical current flows, and an electrical current regulation circuit which controls the magnitude of the electrical current which is extracted from the secondary winding of the transformer according to the collector voltage of the power transistor. Since the most suitable pulse electrical current is made directly from the direct current power supply and is supplied to the base of the power transistor, there is no requirement to provide any DC-DC converter, and it is possible to reduce the size and the cost of the power supply circuit for driving the power transistor.

Abstract: The objective of the invention is to provide an inductive load driving circuit that can prevent occurrence of surge voltage. Output transistor 5 and auxiliary transistor 6 are connected in parallel with each other. When output transistor 5 is turned off, auxiliary transistor 6 is kept on. The energy remaining in inductive load 26 is consumed with current flowing to auxiliary transistor 6. When the output transistor is turned off after the current flowing to output transistor 5 has attenuated, since the counterelectromotive force occurring in inductive load 26 is small, the counterelectromotive power can be clamped by the threshold voltage of auxiliary transistor 6.

Abstract: A driver circuit drives a power element connected to an inductive load. The driver circuit includes an input terminal coupled to a control terminal of the power element through a trigger block, and a voltage regulator block having a circuit node coupled to a first supply voltage reference, as well as to a second supply voltage reference through a capacitor. A voltage comparator stage includes an operational amplifier having an inverting input connected to the circuit node and a non-inverting input is connected directly to a terminal of the power element, such as to the emitter terminal thereof. The operational amplifier also includes an output connected to the control terminal of the power element.

Abstract: A circuit for driving a current into an inductor, which circuit includes at least one main capacitor, a power supply operably connected to the main capacitor, the inductor, and at least two pairs of switches connecting the main capacitor to the inductor, whereby the connection of the main capacitor to the inductor is made in either polarity. Current is driven into the inductor by applying a current to the main capacitor, applying a voltage to the inductor from the main capacitor resulting in generation of inductive energy, and recapturing the inductive energy with the main capacitor at the end of a cycle.

Abstract: A control circuit providing a driving current to a voice coil motor to position a reading and writing head of a disk memory system is described. The circuit comprises a first and a second class AB amplifiers the outputs of which are connected to the terminals of a first resistor in series with the voice coil motor so that a current passes through the voice coil motor and through the first resistor. The circuit comprises a sense amplifier the input terminals of which are coupled with the terminals of said first resistor, a device at the input of which is present a signal which is a sum of an external signal and of an output signal of the sense amplifier. The first amplifier and the second amplifier being driven in inverted phase by an output signal produced by the device.

Abstract: In a semiconductor switch, a voltage detection circuit is provided so as to be in parallel with a first switching element for turning on/off a power supply to a load, in which a voltage detection portion for detecting a drain voltage of the first switching element by dividing a voltage upon a resistance ratio or the like and a second switching element are connected in series to each other. The second switching element is turned on/off in accordance with ON/OFF of the first switching element. Accordingly, detection of a drain voltage is performed normally when the first switching element is in an ON state. When the first switching element is in an OFF state, a leakage current can be reduced by the second switching element.

Abstract: An inductive load driver circuit including a first switch that switches between a conductive state and a non-conductive state selectively applies a first power supply potential to a first side of the inductive load in response to a control signal. A second switch that switches between a non-conductive state and a conductive state selectively applies a second power supply potential to a second side of the inductive load in response to the control signal. The control signal places a control node of the second switch at a lower potential than the second side of the inductive load while the second switch is in the conductive state. In operation, a steady state current in a first direction is driven through the inductive load. The nodes of the inductive load are placed in a high impedance state, after which a steady state current is driven in a second direction through the inductive load.

Abstract: The invention relates to an integrated high power sine wave carrier circuit for outputting a low distortion high power sine wave. The circuit is used for antennas, and especially for antennas in automotive appliances. The circuit comprises a H-bridge (2) with matched power transistors (4, 6, 8, 10), a sine generator (24) for driving the H-bridge and a regulator (22) for sensing the power applied to the antenna and controlling the current amplitude of the sine wave output by the sine generator. The circuit operates under partial time-working, whereby the integration circuit is turned on or off. The circuit therefore comprises a shutdown pin, for shutting the circuit down in order to allow cooling. The partial time operation allows the circuit to be integrated on a single die.

Abstract: A method and apparatus for high voltage applications, with the latest MOSFET technology having limited terminal-to-terminal voltage capability, includes a switch circuit having at least two serially coupled MOSFETs and a two-stage MOSFET connection using a plurality of resistors, and/or a bipolar transistor, and a plurality of diodes. One of the high voltage applications is a high speed write driver in a computer disk drive. The switch circuit switches on/off between zero volt and a voltage higher than a maximum terminal-to-terminal voltage of a single MOSFET which is typically five volts. A required voltage in high voltage applications can be in excess of, for example, 8 or 9 volts.

Abstract: To improve a control circuit for at least one inductive load, comprising a first load branch, which lies between a first voltage terminal and a second voltage terminal and comprises an electronic switch and the inductive load connected in series, the electronic switch lying between a first terminal of the inductive load and the first voltage terminal, and a second terminal of the inductive load being in connection with the second voltage terminal, a freewheeling diode, via which a freewheeling current of the inductive load flows when the electronic switch is open, in such a way that smallest possible fluctuations of the supply current and smallest possible voltage peaks occur at the voltage terminals, it is proposed that there is provided a freewheeling branch which has, as a series connection, a capacitance connected to the first voltage terminal and an inductance connected to the second terminal of the inductive load, and also a freewheeling diode lying between a center tap between the capacitance and the i

Abstract: A method is disclosed for controlling the write head of a magnetic disk storage device. The method includes sinking current from the first terminal of the write head and sourcing current to the second terminal of the write head substantially simultaneously with sinking current from the first terminal so that a first steady state voltage level appears on the first terminal of the write head and a second steady state voltage level appears on the second terminal thereof that are approximately at a midpoint between a high reference voltage level and a low reference voltage level. The common mode voltage of the write head is substantially constant over time.

Abstract: A method and circuit are disclosed for controlling the write head of a magnetic disk storage device. The circuit includes a pull-up device coupled to a terminal of the write head, a current sink circuit which is coupled to the write head terminal and a bootstrap circuit coupled to the current sink circuit. When reversing the direction of current flow through the write head so that current is drawn from the write head from the write head terminal, the bootstrap circuit and the current sink circuit are activated. When the current in the write head nears and/or slightly surpasses the desired destination current level, the bootstrap circuit is deactivated and the pull-up device is thereafter immediately activated for a predetermined period of time.

Abstract: A write circuit selectively provides a write current through a write head in first and second opposite directions. The write circuit is connected to the write head by an interconnect, and has a positive supply level and a negative supply level. A first voltage source provides a first control voltage, and a second voltage source provides a second control voltage. A first resistor is provided between the first voltage source and the interconnect for impedance matching to the interconnect, and a second resistor is provided between the second voltage source and the interconnect for impedance matching to the interconnect. The first and second control voltages provide a transient voltage to the interconnect and provide a subsequent steady-state voltage to the interconnect.

Abstract: A method and circuit are disclosed for controlling the write head of a magnetic disk storage device. The circuit includes a pull-up device and a current sink circuits coupled to each terminal of the write head, for selectively sourcing current to and sinking current from the write head, respectively. A clamp device is coupled to each write head terminal to selectively clamp the write head terminals to steady state intermediate voltage levels. The circuit further includes a control circuit for individually activating the pull-up devices, the current sink circuits and the clamp devices. In particular, when reversing the direction of current flow through the write head from a first direction in which current is provided to the write head via the write head terminal to a second direction in which current is drawn from the write head from the write head terminal, the appropriate pull-up device is activated for a predetermined period of time.

Abstract: A dynamic supply control circuit is provided for a line driver. The line driver has an amplification factor G, receives an input signal voltage, and drives a transmission line having a load RL via a transformer having a turns ratio of 1:n. The circuit includes an input node for receiving an input signal voltage, a supply node for supplying a driving voltage to the line driver, a lift diode coupled between a fixed supply voltage and the supply node, a lift capacitor coupled between the supply node and an output node, and a lift amplifier having the amplification factor G coupled between the input node and the output node. The lift amplifier drives the lift capacitor when the input signal voltage is greater than an input threshold voltage, the input threshold voltage having a value greater than a common mode voltage of the input signal voltage.

Abstract: Providing a semiconductor device for use in a ignition circuit, which prevents an increase in clamp voltage and allows application of a constant voltage across an ignition plug. In a semiconductor device which comprises a transistor and a zener diode connected between a collector and a gate of the transistor, a glass coat layer coating the zener diode is made of silicon oxide.

Abstract: A circuit has first and second switching transistors that are connected between a power supply potential point and ground potential point GND, and controllably turned on and off to drive an inductive load. The circuit is provided with an N-type guardring 27 that prevents effects on other elements formed on the same semiconductor substrate, and the guardring connects to the ground potential point GND. By this structure, a load current in an inverse direction can be flown by a parasitic diode of the switching transistor that is provided on the side of a ground and is in an off state. Also, the operation of a parasitic diode Tr generated in this instance is restrained and the power loss is reduced.

Abstract: The present invention achieves technical advantages as an overshoot circuit (30) for a voltage source/impedance based write coil driver circuit (10) accurately controlling the current (IW)through a coil (LH) that is used to write data to a magnetic medium. The circuit (30) improves the characteristics of the coil.